Self-Rewarding Language Models

Updated 1 July 2025

Self-rewarding language models are LLMs or LMMs that autonomously generate, evaluate, and optimize their outputs using internal reward mechanisms instead of relying on external supervision.
These models enable continual self-improvement and increased scalability across tasks and domains by internalizing learning objectives and evaluation processes.
Applications range from instruction following and mathematical reasoning to automated alignment, multilingual enhancement, and multimodal tasks like vision-language grounding.

Self-rewarding LLMs are a class of LLMs and large multimodal models (LMMs) that autonomously generate, evaluate, and iteratively optimize their own outputs by leveraging internal reward mechanisms rather than external supervision. Unlike conventional approaches that depend on static reward models trained from human feedback or curated data, self-rewarding models establish, assess, and refine their learning objectives internally—enabling continual self-improvement and increasing scalability across tasks and domains.

1. Core Principles and Mechanisms

Self-rewarding LLMs generalize the paradigm of LLM self-alignment by internalizing both the creation of candidate outputs and the evaluation (rewarding) of those outputs. Central principles include:

LLM-as-a-Judge: The LLM, via specially designed prompts, assesses the quality or suitability of its own or other candidate responses, producing structured preference signals (e.g., scores or pairwise comparisons) (Yuan et al., 18 Jan 2024, Lu et al., 2023).
Intrinsic Reward Modeling: Rewards are computed from model-internal signals, such as conditional likelihoods, self-consistency metrics, contrastive prompt outputs, or duality relationships (in multimodal settings), rather than from external reward models or human feedback (Liu et al., 19 Feb 2024, Hong et al., 9 Jun 2025).
Iterative Self-Improvement: Preference data and rewards generated by the model are used in iterative optimization (e.g., DPO, RL, or meta-skill fine-tuning) to drive progressive performance gains. Each training cycle yields models that are both better “judges” and better “candidates” for future iterations (Yuan et al., 18 Jan 2024, Lu et al., 2023).
Task-Generalization: The self-rewarding paradigm has been demonstrated in various settings, including instruction following, mathematical reasoning, multilingual performance, preference alignment, vision-language grounding, document retrieval, and machine translation.

2. Methodological Variants

Several key methodologies embody and extend the self-rewarding paradigm:

Frameworks such as SELF (Self-Evolution with Language Feedback) equip models with explicit meta-skills for self-feedback (critiquing own outputs) and self-refinement (iteratively revising outputs based on feedback). Models are trained to generate, critique, and correct their own responses, catalyzing autonomous evolution without external labels (Lu et al., 2023). This can be formalized as: $\mathcal{L}_{\text{meta}}(\phi) = - \mathbb{E}_{(p, r, f, \hat{r}) \sim D_{\text{meta}}}\Big[ \log \tau_\phi(f|p, r) + \log \tau_\phi(\hat{r}|p, r, f) + \beta \log \tau_\phi(\hat{r}|p) \Big]$ where $f$ is feedback and $\hat{r}$ the refined response.

b. Contrastive and Likelihood-Based Rewarding

The DLMA (Direct Large Model Alignment) framework uses model probabilities under contrastive prompts to score preference pairs: $R(q, a_1, a_2) = \log \frac{T(a_1|p_+, q)}{T(a_1|p_-, q)} - \log \frac{T(a_2|p_+, q)}{T(a_2|p_-, q)}$ where $p_+$ , $p_-$ are prompts inducing helpful/unhelpful responses (Liu et al., 19 Feb 2024).

c. Step-wise and Process-based Rewards

In domains such as mathematical reasoning, process-based self-rewarding leverages step-wise evaluation: at each reasoning step, the LLM acts as a judge comparing candidate steps, producing step-level preference pairs that fuel direct preference optimization (Zhang et al., 5 Mar 2025). This approach improves granularity and reliability of the reward signal, especially for chain-of-thought reasoning.

d. Consistency and Self-Supervision

Methods such as CREAM and SCIR enforce reward signal consistency across iterations or among internal reward models (e.g., generative vs. implicit reward), mitigating bias accumulation and overconfident ranking. The regularized objective may include, for example: $\mathcal{L}(\theta, z) = \mathcal{L}_{\rm SFT}(\theta; \mathcal{D}_S) + \mathbb{E}_{x, y, y'}\Big[ \mathcal{L}_{\rm DPO}(\theta; y, y', x, z) + \lambda \mathcal{L}_{\rm Reg}(\theta; y, y', x) \Big]$ with $\mathcal{L}_{\rm Reg}$ penalizing inconsistent or low-confidence preferences (Wang et al., 16 Oct 2024, Zhou et al., 13 Feb 2025).

e. Multimodal Self-Rewarding

Dual self-reward for LMMs leverages task duality: e.g., using the likelihood of reconstructing the image from the generated caption as a reward for the understanding task, and vice versa for generation: $R_U(Y_T | X_V) = \frac{1}{\|X_V\|} \log \pi_\theta(X_V | Y_T) \qquad R_G(Y_V | X_T) = \frac{1}{\|X_T\|} \log \pi_\theta(X_T | Y_V)$ These mutual likelihoods directly reward cross-modal alignment (Hong et al., 9 Jun 2025).

3. Empirical Findings and Impact

Self-rewarding models have demonstrated:

Benchmark-leading Performance: Iterative self-rewarding can yield improvements matching or exceeding those from human-annotated data or external reward models in both natural language tasks (e.g., AlpacaEval, GSM8K, SVAMP) and specialized domains (e.g., machine translation, mathematical reasoning, vision-language tasks) (Yuan et al., 18 Jan 2024, Zhang et al., 5 Mar 2025, Yang et al., 22 May 2025).
Language and Modality Generalization: Language Imbalance Driven Rewarding achieves simultaneous gains in both dominant and underrepresented languages without alignment tax, and dual self-reward approaches increase both visual understanding and generation fidelity without external labels (Yang et al., 11 Oct 2024, Hong et al., 9 Jun 2025).
Stability via Consistency: Consistency regularization (CREAM, SCIR) prevents reward collapse or drift in smaller LLMs, ensuring reliable alignment across many training iterations (Wang et al., 16 Oct 2024, Zhou et al., 13 Feb 2025).

Framework	Reward Source	Task Domains
LLM-as-a-Judge	Model-internal scoring	Instruction following, general QA
Process-based SR	Step-wise pairwise	Math reasoning
Contrastive DLMA	Prompt likelihood diff	Alignment, safety
Dual self-reward	Cross-modal likelihood	Vision & generation
SSR-Zero	Self-judgment score	Machine translation

4. Distinctive Applications

Automated Reward Design in Robotics: LLMs generate and iteratively refine formal reward functions for DRL agents in robotics, matching expert-tuned rewards (Song et al., 2023).
Automated Alignment without Human Data: SSR-Zero in machine translation, SeRTS in biomedical retrieval, and DRPO for prompt-based self-alignment, remove the need for human-generated reference outputs, using self-judging or dynamic reward signals for continual improvement (Yang et al., 22 May 2025, Hu et al., 17 Jun 2024, Singla et al., 13 Nov 2024).
Self-improving Reasoning Loops: In process-based SR and self-rewarding correction frameworks, models simultaneously solve, critique, and correct, driving up both accuracy and conservativeness in domains requiring reliability (e.g., mathematical problem-solving) (Xiong et al., 26 Feb 2025, Zhang et al., 5 Mar 2025).
Self-directed Multilingual Enhancement: Language imbalance-based self-rewarding turns pre-existing language gaps into a source of preference data, fueling multilingual self-optimization (Yang et al., 11 Oct 2024).

5. Technical and Theoretical Considerations

Training Objectives: Most frameworks leverage direct preference optimization (DPO) losses, optionally augmented with KL regularization or soft labeling based on confidence/consistency:

$\mathcal{L}_\mathrm{DPO} = -\log \left( \frac{e^{\beta (s_\theta(x, y^w) - s_\theta(x, y^l))}}{1 + e^{\beta (s_\theta(x, y^w) - s_\theta(x, y^l))}} \right)$

Reward Extraction and Filtering: To ensure reward reliability, ambiguous cases (low-confidence, inconsistent reward model agreement) may be downweighted or omitted in training. Regularization terms or dynamic thresholding are introduced to prevent overconfident labeling and reward hacking (Wang et al., 16 Oct 2024, Zhou et al., 13 Feb 2025).
Scalability: As self-rewarding approaches obviate the need for large human-preference datasets and can run online with only model outputs, they are computationally and operationally scalable. Their main bottleneck shifts to computational throughput and, for multimodal tasks, modality-specific architectures and data representation.

6. Limitations and Outstanding Challenges

Reward Model Drift and Bias: Inconsistency between multiple internal reward models or between generations can accumulate, necessitating explicit regularization or selection protocols (Zhou et al., 13 Feb 2025, Wang et al., 16 Oct 2024).
Quality Plateau: For some settings, improvements diminish beyond a few iterations, especially in smaller models, or as internal evaluation errors propagate (Wang et al., 16 Oct 2024).
Task Suitability and Transferability: While self-rewarding is suitable for many domains, in settings with highly ambiguous or subjective reward targets, or where programmatic verification is essential, integrating external verification (hybrid supervision) may be needed.
Prompt Design Sensitivity: The composition and engineering of judge and actor prompts, especially for self-judging agents, materially affect the fidelity of the reward signal and susceptibility to reward hacking (Simonds et al., 12 May 2025).

7. Broader Implications and Future Directions

Self-rewarding models represent a paradigm shift toward scalable, autonomous, and continually improving artificial intelligence:

Towards Superhuman Agents: By circumventing the bottleneck of human-limited feedback, self-rewarding LLMs are seen as a pathway to agents capable of surpassing human performance in alignment and reasoning (Yuan et al., 18 Jan 2024).
Unified and Real-time Alignment: Dynamic, prompt-based self-rewarding (e.g., DRPO) enables inference-time, application-specific, and user-personalized alignment without retraining (Singla et al., 13 Nov 2024).
Continual Multimodal and Multilingual Self-improvement: The principle applies beyond language, with extensions to cross-modal grounding, retrieval-augmented systems, and inclusive language coverage (Hong et al., 9 Jun 2025, Yang et al., 11 Oct 2024).
Self-Improvement Loops: Coupling synthetic data generation with self-rewarded RL closes the loop, enabling models to bootstrap skill and continually adapt even in settings with scarce or costly ground-truth data (Simonds et al., 12 May 2025).
Research Directions: Richer reward shaping (finer-grained or process-based), generalizable scoring functions for broader domains, hybrid self- and externally-supervised frameworks, and robust safeguards against reward exploitation remain active areas of inquiry.

Self-rewarding LLMs constitute a rapidly advancing field that augments the autonomy, adaptability, and scalability of LLMs and LMMs. By internalizing both evaluation and optimization, these systems lay a technical foundation for more robust, reliable, and self-directed AI that can operate—and improve—beyond the reach of traditional, supervision-heavy paradigms.